Aircraft cabins are provided with cabin doors for the purpose of passenger ingress/egress. Aircraft cabin door regions are however a source of acoustic and thermal infiltration into the cabin during flight.
Conventionally curtains and/or secondary interior doors have been two solutions for covering and insulating the aircraft passenger cabin, especially executive aircraft cabins, from external noise and low temperatures outside the cabin through the aircraft's main cabin door.
Providing curtains to cover during flight operations the main aircraft cabin door and the integral stairs (if any) provided with the door is very a simple solution. Curtains are very easily installed but are not very efficient in terms of acoustic and thermal insulation. In addition to this disadvantage, aircraft interior cabin curtains are easily soiled and tend to be rather heavy. Moreover, curtains are rather bulky and thus occupy a meaningful amount of interior cabin space that could be put to better use, especially in smaller executive aircraft cabins.
A secondary door is a more complex solution than curtains. In addition, mounting a secondary door in relation to the aircraft cabin main door is accomplished at a substantial weight penalty since the weight of the secondary door is not insubstantial. Generally, in order to increase insulation effects of a secondary door the thickness of the door must be increased which in turn increases its weight. Thus, providing a secondary door as a solution to enhanced cabin insulation in the main cabin door area is a careful balance between the weight, volume and insulation efficiencies of the secondary cabin door.
It would therefore be especially desirable to enhance an aircraft cabin's acoustic and/or thermal insulation in the area of the main cabin door that minimizes (if not eliminate entirely) many of the problems associated with the conventional solutions described above. It is towards fulfilling such a need that the present invention is directed.